Stannite

stannite [′sta‚nīt]

(mineralogy)

Cu₂FeSnS₄A steel-gray or iron-black mineral crystallizing in the tetragonal system and occurring in granular masses; luster is metallic, hardness is 4 on Mohs scale, and specific gravity is 4.3-4.53. Also known as bell-metal ore; tin pyrites.

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Stannite 

a mineral of the sulfide class, with the chemical composition Cu₂FeSnS₄. Stannite contains 29.58 percent Cu, 12.99 percent Fe, 27.5 percent Sn, and 29.8 percent S, as well as admixtures of Zn, Sb, Cd, Pb, and Ag. High-temperature stannite, which occurs in pegmatites, quartz-feldspar veins, and greisens, has isometric symmetry; low-temperature stannite, a widespread mineral of cassiterite-sulfide deposits, has tetragonal symmetry and a crystal structure similar to that of chalcopyrite.

Stannite occurs as fringes around grains of cassiterite and chalcopyrite, as solid granular masses, and as faceted grains of pseu-dotetrahedral and more intricate shapes. The mineral has a steel-gray color with an olive-green tint. Its hardness on Mohs’ scale is 3–4.5, and its density is 4,300–4,500 kg/m³. Stannite is brittle and a good conductor of electricity. It is formed in hydrothermal deposits and, less frequently, in pegmatites and greisens in association with wolframite, chalcopyrite, cassiterite, sphalerite, gray copper ore, and pyrrhotite.

The largest known accumulations of stannite in the USSR are in Primor’e Krai (Dal’negorsk deposit), the Northeast (Kheta), and Central Tadzhikistan (Mushiston). Abroad, there are large deposits in Bolivia (Potosí, Atocha). In sufficient concentrations, stannite may be used as a tin ore.

A. B. PAVLOVSKII